This invention relates to improvements in turbomachinery and in particular, to an improved structure for admitting a cooling medium thereinto.
There are many known manufacturing applications wherein large quantities of relatively high temperature (for example 1,000.degree. - 1,200.degree. F) waste gas are discharged as a result of the particular process involved in such application. To achieve an increase in the efficiency of the process, and more importantly, to conserve energy, it is extremely desirable to employ the high temperature waste gas to drive a power recovery turbomachine. Heretofore, there have been many problems associated with power recovery applications of this type due to the general nature of the waste gas used as the motivating fluid. For example, the gas very often is "dirty" due to large quantities of foreign particles entrained therein. To prevent rapid erosion of the various parts of the turbomachine, separators or similar equipment have been employed to remove the foreign particulate matter entrained in the gas stream prior to its entry into the turbomachine.
Additionally, due to the relatively high temperature at which the gas is delivered to the machine, it is generally necessary to supply a cooling medium thereto to maintain the components thereof below critical temperatures. The waste gas is almost always flammable; therefore, it is necessary that the cooling medium be an inert gas to prevent ignition of the waste gas within the turbomachine. Since steam is generally available at applications employing power recovery machines of the type under discussion, the steam may be utilized as the cooling medium. As the temperature of the various components of the turbomachine are operating at relatively high temperatures, it is necessary that the steam be admitted into the machine in a manner whereby localized overheating or overcooling of any of the components is prevented. To achieve the foregoing desiderata, the steam should preferably be placed in a substantially superheated state prior to its contacting any of the turbomachine's relatively hot components. Furthermore, the velocity of the cooling medium should be maintained at a substantially high rate to obtain convection cooling of the components.